CR2 News Report | Heatwaves and Extreme Roulette. What Does the Summer of 2024 Hold, and Those to Come?

  • A study has concluded that heatwaves have increased throughout the country over the past four decades, primarily in the valleys of the central-southern region of Chile.
  • These events have adverse effects on ecosystems, biodiversity, human health, and create favorable conditions for the spread of forest fires, so preventive actions must be taken.

By CR2 Communications

A month ago, the Copernicus European Union observatory revealed that the global surface temperature of the planet exceeded, for the first time on record, 2 °C above pre-industrial values. This occurred on November 17 and 18 when temperatures reached 2.07 and 2.06 °C, respectively. The institution also noted that this November was the warmest month recorded, as was the June-July-August period of this year.

Simultaneously, the Barcelona Institute for Global Health recently published a study in The Lancet linking the extreme heat of the European summer in 2022 to a mortality burden of 70 thousand deaths.

High temperatures and heatwaves are not foreign to the southern hemisphere. In Brazil, for example, the highest temperature ever recorded in its history was 44.8 °C in the city of Araçuaí on November 19, 2023. Concerns arise about what might happen in Chile during the summer period, not only due to temperature extremes but also due to the advancement of fires (as seen in the past summer and more recently during the second week of December) and the impact of the current El Niño phenomenon.

René Garreaud, deputy director of the Center for Climate and Resilience Research CR2, mentioned that “when you look at history, you see that half of the El Niño years have temperatures above normal, while the other half is below average. Therefore, making a forecast with this range, which is almost fifty-fifty, is like tossing a coin.”

This idea is reinforced by Martín Jacques, professor at the University of Concepción, who states that an El Niño year “does not necessarily imply a hot summer in the central zone of Chile. It’s a belief that has taken root but is not based on observations.”

A Roulette of Extreme Conditions

Regarding heatwaves, Garreaud commented that in the country, they are associated with a very particular phenomenon: the Puelche, a wind that comes from the Andes in southern Chile and flows from east to west.

The Puelche collects air from Argentina or the upper troposphere and transports it to the Chilean valleys, where it heats up even more as it descends. But in the context of climate change, where the global air is already warmer, it will generate even hotter events. “If the same Puelche happened in the 80s, it would have produced a heatwave of 35 degrees Celsius, but in 2023 or 2024, the heatwave will be more intense because the current air is at a higher temperature. Therefore, climate change is causing heatwaves to be more prolonged, intense, and frequent,” he explained.

The researcher commented that a roulette is a good metaphor to explain extreme events like heatwaves in the context of climate change. “Imagine we have a roulette of atmospheric weather where there are sectors with cold, cool, temperate, and warm temperatures. If you throw a ball, it will fall into one of those sectors, which in the past were similar. But with climate change, the cold sectors of the roulette are decreasing in number, while sectors with extremely warm temperatures that did not exist before are appearing. If you throw the ball now, it may fall into these spaces. Therefore, climate change increases the options for the warmer side, which is related to high-temperature risk situations. On the other hand, risks associated with extreme cold are disappearing,” Garreaud stated.

A recent study published in the journal Weather and Climate Extremes addressed heatwaves in Chile, providing a historical balance since 1980 in the context of climate change.

The research concluded that heatwaves have been increasing since the 1980s, and this trend will continue in much of the national territory. Along with this, it was determined that periods like the megadrought increase these phenomena, leading to up to four more events per decade compared to a normal period.

Álvaro González-Reyes, researcher at the Institute of Earth Sciences of the Austral University of Chile and the lead author of the research (which also involved René Garreaud and Martín Jacques), explained that the upward trend in heatwaves is due to various mechanisms, such as the intensification of the Pacific anticyclone and its southward migration.

“The Pacific anticyclone is intensifying due to climate change, and this generates higher atmospheric pressure, which translates into more clear days or low cloud coverage. Added to this is the Puelche, which is like placing a hairdryer with hot air flowing at different speeds,” he commented.

The geographical extension of the increased frequency of heatwaves would include the Andes in the northern zone of Chile, Patagonia, and Tierra del Fuego, but they will be concentrated in a particular area. “One of the areas where the increase in this phenomenon is most notably appreciated is the valley of the central-southern part of the country, which coincides with the area where the highest temperatures are recorded in the summer. Therefore, it is an area where we must focus our preventive efforts against possible impacts from the rise in the frequency and intensity of heatwaves and extremely hot isolated days,” said Martín Jacques, who is also a principal investigator of the Center for Climate and Resilience Research CR2. Meanwhile, there would be no evident increase in heatwaves in coastal areas due to the thermoregulatory effect of the Pacific Ocean.


Heatwaves also affect forest fires. The mentioned article indicates that in January 2017, the temperature in central-southern Chile persistently exceeded 30 °C. This, coupled with low relative humidity and wind disturbances, led to the burning of about five thousand square kilometers of native forests and exotic plantations, an extension ten times larger than the average of the last forty years. A similar situation occurred with the megafires in February 2023.

And even if an ecosystem is not directly affected by fires, it is still impacted by heatwaves and extreme temperatures. González-Reyes explained that trees in Patagonian forests, accustomed to moderate temperature conditions, or vegetation in the Valdivian rainforest, requiring abundant water, can be severely affected by persistent heat, as it increases the transpiration of the forests, and that water evaporates into the atmosphere. “And heatwaves not only affect forests, but there is also an as yet unquantified impact on bodies of water such as lakes and wetlands, as well as water reserves like snow, mountain glaciers, and our extensive ice fields such as the Northern and Southern Ice Field in Patagonia,” he emphasized.


Considering the upward trend in heatwaves and the current ability to predict them with approximately one or two weeks’ notice, González-Reyes suggests the need to use this information to generate alert plans for their impact on biodiversity, particularly for forest fires. Some measures that can be considered include closing national parks and preparing the healthcare system to avoid collapses.

At the same time, he proposes to develop an ordering that aims at resilient territories. “There are areas that are being highly affected by this type of events, such as crops or plantations that are highly flammable. It’s essential to remember that heatwaves are not only related to temperature increases but also to drought, and if these areas have less moisture content in their soils, a domino effect occurs that can end in megafires, as happened in January 2017,” he said.

“Currently, there are about five thousand forest fires in Chile during the summer season, and the climate will become more favorable for them to spread, so there is a high probability that one of these fires will combine with a heatwave and become a megafire,” warns René Garreaud, advising to do everything possible to reduce these thousands of ignition points through prevention and education.

“Before, these atmospheric conditions were exceptional, but today they are much more recurring, and we must be prepared because the roulette with extreme conditions can hit us every year,” concluded the deputy director of CR2.